Heretofore, since resins such as typically plastics are excellent in corrosion resistance and transformation acceptability, it is often that the surfaces of various substrates such as iron, aluminium and the like are coated for protection with resins such as plastics, taking the advantages of the properties of those resins, and thereafter the coated substrates are worked and shaped.
In this case, a thick coating may be formed by casting a molten plastic material onto a substrate; however, it is difficult to form a uniform thin film having a thickness of, for example, at most 100 microns. A resin such as an ultra-high-molecular weight polyethylene or the like has poor fluidity, to which, therefore, a coating method that comprises melting and fluidizing a powder could not be applied.
As a thin coating method for an objective substrate with a resin or the like, there is known a vapor deposition method or the like, which, however, requires special facilities and is not applicable at all to a large substrate; and therefore, in general, a resin solution dissolved in a solvent is applied to such a substrate.
The solvent-based resin coating has many problems in that the solvent may degradate resins or may damage substrates and the solvent may scatter to have some negative influences on the workers and on the environment; and if possible, solvent-free resin coating is desired.
On the other hand, regarding thin-film coating with an inorganic material, HVOF spraying (high-velocity oxy fuel spraying), which requires no solvent at all and which readily attains spray coating of a substrate with an inorganic material using a spray gun, has achieved many satisfactory results.
A technique of spraying a substrate with a heat-resistant resin such as PEEK (polyether-ether ketone) or the like through such HVOF spraying is disclosed in the following references (see Patent References 1 and 2). However, according to these methods, it is indispensable to previously roughen the surface of the substrate and/or form on the substrate surface a bonding layer having good adhesiveness to resin, for which, therefore, the working steps may increase and the methods could not exceed the category of the above-mentioned coating technique. In addition, the resin coating members to be obtained are substantially those where the bonding layer stands in the interface between the coating material and the substrate. Further, in mere melt coating of the roughened surface with PEEK by HVOF spraying, the coating material could not break into the fine irregularities of the substrate surface, and strong coating could not be realized.    Patent Reference 1: JP-A 2000-96203    Patent Reference 2: JP-A 2007-175881
In the above-mentioned background, the subject matter of the present invention is to solve the prior-art problems and to provide a coated member in which the coating resin and the substrate strongly adhere to each other by a physical structure, and a resin coating method for producing the coated member not requiring any coating treatment at all.